This invention is related to a novel synthesis of alpha-alkoxycarboxylic acids which, with known technology, could otherwise only be made in the laboratory, usually with considerable difficulty. By the term "alpha-alkoxycarboxylic acids" I refer also to alpha-phenoxycarboxylic acids, alpha-thioalkoxycarboxylic acids, and alpha-thiophenoxycarboxylic acids. This invention is more particularly related to the preparation of beta-substituted alpha-alkoxycarboxylic acids from which can be derived a wide variety of (a) substituted acrylic acids which are both alpha and beta substituted, and (b) substituted acrylamides which are both alpha and beta substituted.
The alpha-alkoxycarboxylic (or "2-alkoxycarboxylic") acids and their esters have been highly regarded for their utility in perfumes and other cosmetics; paints, coatings and impregnants; textiles; and, in the paper industry. The acids and esters have also been used on a laboratory scale, as a starting material for the preparation of various acrylates some of which, if they were commercially available, could provide polymers with a wide range of physical and chemical properties not readily available in available acrylates and methacrylates. As is well known, the physical and chemical properties of polymers of acrylic acid esters and methacrylic acid esters depend to a large degree on the type of alcohol from which the esters are prepared, and, the length of the sidechain. Little is known about the properties of acrylates with substituents on the beta carbon, simply because making compounds with such substituents was impractical. Still less is known about polymers which may be formed from substituted acrylic acids having substituents on both the alpha and beta carbon atoms.
Thus, despite the ability of acrylate and methacrylate esters to copolymerize with nearly all types of monomers, which ability has resulted in extensive industrial use of the esters, the fact remains that, because of the unavailability of all but a few acrylate and methacrylate esters, only the few are presently in wide use. This is so despite the knowledge that some polymers which have more desirable properties for specific applications than poly(methyl methacrylate) ("PMMA") or copolymers of methyl methacrylate and other esters may even be more economical than PMMA. It is undisputed that the bulk availability of only a few substituted acrylates has precluded the commercial exploitation of many novel acrylate-containing polymers, particularly those acrylates with substituents on both the alpha and beta carbon atoms.
In an article titled "The Synthesis of alpha-Alkoxyisobutyric Acids and Alkyl Methacrylates from Acetonechloroform", by Ch. Weizmann, M. Sulzbacher and E. Bergman, J.A.C.S. Vol 70, p 1153-1157, there is disclosed a preparation starting with alpha-trichloromethyl alkanol (referred to in the article as `acetonechloroform`, and hereinafter, for brevity, as `TCMA`), which must first be prepared, and the preparation of which usually entails considerable difficulty. Though once the TCMA is prepared, it readily reacts vigorously with a solution of potassium hydroxide in alkanol, it is acknowledged in the reference that TCMA suffers undefined decomposition to acetone, carbon monoxide, phosgene and formic acid. It is the difficulty of preparing alpha-trichloromethyl alkanol which limits the applicability of the disclosed Weizmann et al reaction to alpha-isobutyric acid. Yet the preparation of the TCMA is critical because the disclosed reaction will not proceed if acetone and chloroform are substituted for the TCMA. It is the difficulty of making and using TCMA which limits its use in the disclosed synthesis to the laboratory.
A phase transfer catalyzed reaction known as the "ketoform reaction" is disclosed in my U.S. Pat. No. 4,167,512, and illustrated in one particular example by the reaction of a N,N'-alkyl substituted ethylene diamine with acetone and chloroform; and, in another example, with o-phenylene diamine reacted with cyclohexanone and chloroform. The reaction product in each example is a 2-keto-1,4-diazacycloalkane. The patented synthesis also proceeds by virtue of a phase transfer catalyzed reaction mechanism in which an amine, a haloform and a ketone are separate reactants, but the patented synthesis does not envision the use, as yet another reactant, of an organic compound having at least one reactive hydroxyl or thiol group.